The system is controlled by a pair of sensors in the paper which serves as the parking lot. There are three sheets of heavy stock, the top and bottom both have aluminum foil on them, with the center layer as a separator. There are holes cut in the separator where the hash marks are seen above. By adding a little pressure to the car when you drive it up to the gate this completes a circuit instructing the Arduino that there’s a vehicle in position.

You can see a demonstration, as well as the guts of the build, in two videos after the break.

[Jeff] and his wife put together a firefighter themed birthday celebration for their son. As he’s not entirely handy in the kitchen, [Jeff] decided not to lend a hand with the baking or cake decorating. But he didn’t forego the opportunity to combine a couple of different projects to make a Matchbox car launcher that responds to emergency band radio.

Since he’s an amateur radio enthusiast he already had a scanner to monitor the air waves. Apparently there’s a band just for relaying dispatch messages to emergency vehicles. He set the radio equipment to only monitor that channel. An Arduino was added to the mix, taking measurements of the voltage level on the scanner’s audio output. When it’s driven high enough the Arduino trips the toy car launcher.

The car launcher itself is a pretty nifty setup. There are five chutes at the top of a ramp that each fit a car. A sliding gate holds them in place, but can be removed one slot at a time by a geared motor. The addition of a poster board facade and two flashing red LEDs makes the setup look right at home with the other party decorations.

See a call come into the station in the clip after the break. We don’t have a category called “fun parenting” so “toy hacks” will have to do.

This tiny line-following robot is quite impressive. It’s [Ondrej Stanek’s] second take on the design, which he calls PocketBot 2. Just like the earlier version, this robot is small enough to fit in a matchbox, but it’s received several upgrades in this iteration.

The coin cells that ran the previous version have been replaced by a rechargeable Lithium Ion cell. The ATmega8 which controlled the first robot has been swapped out for an ATmega128 running at 32 MHz. You won’t find an IR receiver on this one either, it’s been traded for a Bluetooth module which adds a quantum leap in functionality. For instance, the graph in the upper left of this photograph shows the reflective sensor data readings used to follow the line.

There’s all kinds of great engineering in this design, which is shown off in the video after the break. One of our favorite parts is that the axles are attracted to the center of the robot by one rare-earth magnet. This keeps the rubber tires pressed against the motor spindles rather than use a gearing system.

[Paul] wrote in to show us this little project he did for his kids. His children love playing with their toy cars. In an effort to give them even more fun while playing, [Paul] built a stop light for them. He’s using an ATtiny13 to run them and has the source code available on his site. Not only did the kids get a new toy, he got an excuse to go build something in his workshop.

[atduskgreg] posted this interesting setup to flickr. He’s using two toy cars as a switch. He has wired into their metal undercarriages so when they collide, the circuit closes. We’ve seen somepretty nifty home made interface items, but usually they are posted with a clear purpose or a project. This one is a little puzzling. Does he intend to keep using the cars or was he just fooling around? Is he working on a toy that does something when they crash? Was he merely bored and wanted to see what he could attach to his Arduino. We may never know.